GB1256420A - Electro-optical character display or photocomposing devices - Google Patents

Abstract

1,256,420. Photographic type-composing. INTERNATIONAL BUSINESS MACHINES CORP. 5 June, 1969 [18 June, 1968], No. 28511/69. Heading B6W. An electro-optic photocomposing machine comprises a light source producing a collimated and polarized beam 12, a vertical electro-optic deflection 110, a horizontal deflector 114, a stationary character matrix plate 13, a vertical deflector 117, a horizontal deflector 118, and a stationary film 14. The deflectors 110, 114 may each comprise three birefringent crystals, each twice as thick as the preceding one and each having at its input side an electro-optic device comprising an electro-optic crystal between a pair of transparent electrodes, which device rotates the plane of polarization 90 degrees when a potential is applied across the electrodes. The beam may thus be deflected up to seven steps vertically and horizontally so as to pass through any of 64 selected characters. The deflectors 117, 118 may comprise seven birefringent crystals, giving a theoretical grid on the film of 128 x 128, which is reduced in that the reference lines for zero deflection must be displaced by seven positions, since the deflectors 117, 118 cannot reverse any deflection by the deflectors 110, 114. The driving mechanism for closing the switches for the electrodes of the deflectors 110, 114 are controlled by character selection registers 119, 120, whereas the driving mechanism for the deflectors 117, 118 is controlled by both the registers 119, 120 and character positioning registers 123, 124, the outputs of which are added or subtracted by devices 125, 126 according as the direction of deflection by the deflectors 117, 118 is opposite to or the same as that by the deflectors 110, 114. In the case of subtraction, a correction factor of seven vertical and seven horizontal steps is inserted.